Inductance device



Dec. 6, 1927. 1,651,703

F. o. HARTMAN INDUCTANCE DEVICE Filed July 8, 1925 2 Sheets-Sheet l WM FIN VEN TOR.

fazyafi'mazz m a. M

ATTORNE Patented Dec. 6, 1927.

* UNITED STATES PATENT OFFICE.-

FRANK O. I-IARTMAlI', OF MANSFIELD, OHIO, ASSIGNOR TO THE HARTMANELECTRICAL MANUFACTURING COMPANY, OF MANSFIELD, OHIO, A CORPORATION OFOHIO.

INDUGTANCE DEVICE.

Application filed July 8,

circuit arranged in such manner that the lines of force may beeffectively employed within. a concentrated area for transferring energyfrom one electron tube circuit to another with minimum loss.

Another object of my invention is to pro vide a series of couplingdevices for interlinking the input and output circuits of severalelectron tubes comprising an amplifier which will limit the magneticfields emanating from the coupling coils to the coupling coils per seand substantially prevent the straying of magnetic lines fromv the.

coils which might otherwise tend to interlink. other portions of thecircuits of the amplifier resulting in the production of undesired.interfering currents.

Another object of my invention is to provide a construction of couplingdevice by which energy may be transferred from one electron tube circuitto another in an amplification. system with lower distributed capacitythan is present in coils heretofore available inthe art, and with a.concentrated magnetic field linking the windings of the coupling devicefor the efficienttransfer of energy from one circuit to another.

Still another object of my invention 1s to provide a. construction ofcoupling device arranged to produce a magnetic field concentratcd withinthe coupling device to secure the maximum transfer of energy from onecircuit to another with minimum dielectric losses and with maximumseparation of the high and. low potential ends'of the coils.

Still another object of my invention is to provide a self supportingcoil structure so wound. that a magnetic field is produced which issubstantially concentrated within the area of the winding for thereduction of stray magnetic lines of force and with the maximum.separation of high and low potential points of the winding.

1925. Serial N01 42,275.

A further object of the invention is to provide a coupling system forinterlinking the input and output circuits of an amplifier in which atleast one of the coupling coils has an equal number of external fieldsof substantially equal intensity which operate to substantially preventcoupling with other coupling systems in the amplifier.

A. still' further object of my invention is to provide a construction ofself-supporting inductance or transformer wherein the coil may bemechanically supported by means extending across a diametrical linethereof to rigidly position the turns of the coil in such manner thatthe physical size of the winding may be concentrated within a small areawith inherent advantages in the reduction in electrostatic capacityeifects and the concentration of the magnetic field enclosed by theturns of the winding.v

A still further object of my invention is to provide a' self-supportingmodified figure of 8 coil. so latticed across its center that the centersection does not build up to a height of greater extent than the heightof each lobe of the figure of 8.

A still further object of the invention is to provide an electron tubeamplifier of great sensitivity having coupling coils interlinking theinput and output circuits of the several tubes in which the couplingcoils are not susceptible to the radiation of signaling energy fromnearby sources, such as local broadcasting stations, thereby eliminatinginherent interference of signals in the amplifier.

I have illustrated my invention with particular reference to radiofrequency amplifiers for use in radio reception, Heretofore in the artit has been difiicult to construct radio frequency amplification systemswhich would be stable in operation and free from inherent oscillation.Various methods have been proposed for suppressing undesiredoscillations in amplification systems all of which. have introducedcomplications in manufacture and have required the skillful balancingthe electron tube circuits for the prevention of the undesiredoscillatory current in the amplification system. By my present circuitarrangement I provide .a structure of coupling device having its,windings so arranged that they may be interposed between the input andoutput circuits of. electron'tubes connected in the tuning circuit of areceiving system and by their inherent construction prevent the settingup of undesired oscillatory currents. I secure these results byconstructing the windings ol the coupling devices in such manner thatthe fields thereof which may extend tor-any considerable distance frontthe coils or any stray magnetic lines of force which may exist about thecoupling device are opposed by substantially equal and opposite magneticlines oi force giving a resulta substantially nil coupling between thestray magnetic lines oi. force. The elimination olthe magnetic couplingbetween stray magnetic fields ei'nanating from the coupling devicesprevents the setting up of undesired. oscillatory currents in theamplification system in so tar as the magnetic coupling between thecircuits is concerned. In an amplification system the magnetic couplingbetween the several tube circuits is one of the important factors whichtends to produce undesired oscillatory currents. The coupling coils areso constructed that they have a north andsouth pole at the same end andit the north pole of one coil is tending to couple with the south poleof a second coil, the south pole or the first coil is tending to thesame extent to couple with the north pole of the second coil and theseforces couple and oppose each other.

Myinvention will be more clearly understood trom the specificationhereinafter following by reference to the accompanying drawings,wherein:

Figure 1 shows the application of the coupling devices of my inventionto a radio lirequency amplification system in a radio receivingapparatus; Fig. 1" shows a modified arrangement oi? the coupling systemin which the primary and secondary windings are formed of inductivelyrelated figure of S windings; Fig. 2 is a theoretical View showing themethod oi. winding the figure of 8 coupling inductances; 3 is a planview illustrating the construction of the coupling inductances; Fi i isa side elevation of the coupling inductances illustrated in Fig. 3; Fig.5 is a detail view showing one of the arrangements for supporting theturns of wire making up the inductances; Fig. (l is an enlargedfragmentary view showing the central supporting web formed in the coilstructure.

Referring to the drawings in detail, I have shown a radio receivingsystem for a radio frequency amplification circuit wherein theprinciples of my invention have been illustrated. Reference character 1designates the receiving antenna system and reference character 2 showsa ground connection. In the antenna ground circuit I position one of thefigure 0t 8 inductancer dcsi nated by rererence character 3 as havinglobes 4 and 5 with a connection 6 "from the antenna 1 to a point alongthe lobes i. The inductance 3 is tuned by me ns of variable condenser 7which forms with the inductance a tuned input circuit for electron tube8 comprising the first stage 01'? radio trequency amplification. In theoutput circuit of the electron tube 8 the primary iuding S) of acoupling device 10 is positioned. A secondary winding 11 of the couplingdevice 10 is tuned by variable condenser 12 to the frequency of theincoming signaling energy. The coupling device 10 may have its windingssimilarly constructed oi figure ol 8 coils as shown more clearly in F i1- or only one of the windings may be a figure of 8 coil, while theother winding may be cylindrical or D shaped as I have represented indotted lines at 14: in Fig. 3. The windings may be built up with thesame type of winding forming the figure 0t 8 coils illustrated in Fig. 1by continuing the structure oi the windings which I have illustrated inFig. l, although such other secondary winding may be disconnectedelectrically from the cooperating winding. lVith further reference toFig. l of the drawings, the figure of 8 inductance tuned by variablecondenser 12 forms the input circuitof electron tube 15, comprising asecond stage oi radio frequency a1nplification. The output circuit ofthe electron tube 15 is coupled with the input circuit of an electrontube 16, functioning as rectifier by virtue of a coupling system 17. Thecoupling system 17 is similar to the coupling system 10 in that itincludes a primary winding 18 and a figure of 8 secondary winding 19tuned by variable condenser 20. A "rid leak and grid condenser 21 areconn cted in the input circuit of the detector tube 16. The outputcircuit of the tube 16 includes primary winding 22 of audio frequencytransiforn'ier 23, and the secondary winding 24 0t transformer 23delivers rectified energy to the audio frequency amplification tube 25.A suitable responsive device 26 is connected in the output circuit ofthe audio frequency amplifier. The anodes for each of the tubes aresupplied from a source 27. The cathodes of the tubes are heated from asource 28, the filament temperature of tubes 8 and 15 being controllablethrough rheostat 29, while the filament electrodes ol tubes 16 and 25are regulated through rheostat 30. The method of winding the figure of 8coils for eliniiiuating stray magnetic fields and at the same timeproviding a seltsupporting winding is clearly illusti ated in connectionwith Fig. 2- ol the drawings. In this diagram the inductance ll has beenillustrated as comprising'a cylindrical portion 31 and a laterallyextending diametrica portion The turns of the inductance are supportedupon themselves by weaving the turns of the inductance along the lateralill) or ains 33 '34 35 and 3-7 are tern orari'l provided and theinductance wound comaround the left hand lobe.

mencing for example as illustrated by arrow 38 and passing on the righthand side of spoke 33 over the left hand side ofboth spokes, and 35,be'tw-centhe spokes 35 and 36 and then tangentially along the right handside of spokes and 3? where the winding passes around the left hand lobein the direction illustrated at 39. At the top of the left hand lobe,the wire passes tangentially along the left hand side of spoke or pin 33and between pins 33 and 3d, and then tangentially along the right handsides of spokes 3i and 35 between spokes 35 and 36 and downwardlytangent to the left hand side of spokes 36 and 37 thence upwardly aroundthe right hand lobe as designated at lO. At the top of the right handlobe the conductor passes tangentially to the left hand side of thespokes or pins 33 and 34 and between pins 34 and 35 in a downwarddirection tangent to the right hand sides of spokes 35 and 36 passingbetween spokes'36 and 3? and upwardly at 41 This winding again passesdownwardly through the center passing along the right hand side ofspokes and 3% between spokes 34 and 35 and down the left hand side ofspokes 35 and between spokes 36 and 37 and down the right hand side ofspoke 37, and turns upwardly around the right hand lobe on the linemarked 56. again follows the path taken by conductor 38. in this mannerthe figure of 8 inductance has the magnetic field thereof concentratedin a small area and the winding is self-supporting. The spokes or pins33, 34:, 35, 36, and 37 may be employed only during the manufacturingprocess, that is, during the winding operation and after the coil iswound the pins may be removed. By rea son of latticing the centralportion of the coil in the manner described the turns at the center ofthe figure of 3 do not build up to a height greater than the height ofthe turns around each lobe of the coil. The cylindrical portions of theturns 31 may be supported by means of the strips 2, 43, l 45, 46, ll",4-8 and 49, which extend laterally along the coil 11 and may envelopboth sides thereof. lhe strips are preferably of celluloid or insulatingmaterial which may have the surface thereof softened in such manner thatthe turns 11 may be impressed into the surface of the material. I findthat amyl-acetate is desirable for this purpose. The surface of thecelluloid is softened enabling the material to be pressed between theturns of the wire as represented more clearly in l? 5. The turns havebeen designated at 11 having insulating material 11 thereabout. Thecelluloid material 45 has its sur- The winding then' face, softened, sothat the material, thereof may be pressed between the turns as indicat-ed more clearly at 50.

As heretofore indicated the primary winding' may be D slilapedasrepresented in- Fig, 3- by reference chara.eter-14,the turn-s beingsupported by vertically extending strips, 531, 52, 53, 5d, and 55,similar to the vertically extending strips which support the secondarywinding.

By virtue of the figure of 8 formation of the turns of the laterallyextending woven form for the winding, the stray electromag netic fieldsare substantially eliminated and the inductance arranged to besubstantially self-supporting facilitating the manufacture of thecoupling devices. A portion of each turn is curved in a cylindricalformation while another portion lies in a serpentine path serving tomechanically support the cylindrical portion of the winding and preventthe central portion building to a greater height than the circularportions.

While I have described my invention in certain particular embodiments, Idesire that it be understood that modifications may be made and that Iintend no limitations upon the invention other than those imposed by thescope of the appended claims.

What I claim and desire to secure by Let ters Patent of the UnitedStates is as follows:

1. An inductance device comprising in combination a winding having thecontour thereof substantially in cylindrical formation and formed with aserpentine web por tion along a diametrical line of said cylindricalformation, the turns along said serpentine web portion serving tomechanically support the turns in said cylindrical forma tion insubstantially parallel planes, and a plurality of strip membersextending parallel to the axis of said cylindrical formation in whichthe turns are embedded for rigidly bracing said inductance device.

2 An inductance device comprising in combination a substantiallycylindrical coil having the turns thereof built one upon another, a webportion of said coil extending laterally across a diametrical linethrough said cylindrical coil, the turns of said coil extending aroundthe circumference thereof and laterally across said web portion in wovenformation in planes substantially parallel with the planes containingthe turns of said cylindrical coil, the turns within said web portionserving to mechanically support the turns of the said cylindrical coilin substantially parallel planes and strip members embedding the turnsof said cylindrical coil, said strip members extending parallel to theaxis of said coil for rigidly bracing said inductance device.

3. An inductance device comprising in combination a winding having theturns thereof Wound in a modified figure of 8 shape with a pair of lobeportions on opposite sides of a diametrically extending Web portion,said Web portion being latticed a plurality of times across the centerof said coil in a serpentine path limiting the height of the centerportion substantially equal to the height of each lobe portion and meansembedding the turns of said lobe portions along lines parallel to theaxis of said coil for increasing the rigidity of said inductance device.

FRANK O. HARTMAN.

